Kendall Jenner Spends Mother’s Day in Skimpy String Bikini: See Her Sexy Swim Style!

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A photo posted by Kendall Jenner (@kendalljenner) on May 10, 2015 at 4:27pm PDT

Flaunting her fitness on Mother's Day!

Yes, Kendall Jenner (along with her little sister, Kylie) adorably wished mom Kris a happy holiday with a balloon masterpiece on Sunday, May 10—but the rising model also stripped down to catch some rays, too!

Jenner,19, showcased her lithe model frame while wearing a blue and white string bikini and lounging with Hailey Baldwin on a swan float. Sharing a photo of herself and Baldwin as bathing beauties, the Estee Lauder model captioned the shot with a BFF emoji (aka two girls holding hands).

kendall jenner
Kendall Jenner worked a rocker crop top and white skinny jeans while leaving a gym with Justin Bieber on May 10. AKM-GSI

That same day, Jenner and Baldwin, 18, hit the gym with Justin Bieber, who was snapped escorting the ladies back to Jenner's car post-workout. Giving Taylor Swift's impeccable gym ensembles some fierce competition, the reality TV star looked especially fresh in a sleeveless Lynyrd Skynyrd crop top, white jeans, and nude heels.

Which of Jenner's sexy off-duty model looks do you prefer? Tweet with @UsWeekly using the hashtag #stylebyUs!

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